1. Field of the Invention
The invention relates to an alkali soluble polymer and a positive working photosensitive resin composition using the same, which can be available in the filed of photo-resist and the like.
2. Related Art
Patterned transparent films have been used in many parts of display devices such as spacers, insulating films, and protective films and many positive working photosensitive resin compositions have been proposed for these uses (see, e.g., JP 51-34711 A; JP 56-122031 A; and JP 5-165214 A). In addition, there is known a positive working photosensitive resin composition containing a polymer using 4-hydroxy styrene as a monomer (see, e.g., JP 52-41050 B).
In general, electronic parts, such as liquid crystal display devices having thin-film transistors and solid-state image sensing devices are provided with insulating films for insulating between electric wirings arranged in layers. As a material that forms the insulating film, a positive working photosensitive resin composition, that allows the formation of an insulating film having a desired pattern by a small number of steps, is widely used. In addition, the positive working photosensitive resin composition requires a wide process margin in the process of forming an insulating film. Further, an insulating film or a display device using the positive working photosensitive resin composition absolutely require in a latter step of a production making a contact with a solvent, an acid, an alkali solution, or the like by dipping and treating with heat.